Swim fin

ABSTRACT

A swim fin having a support strap attachable to the forearm of a user with a lower portion of the strap extending transversely of the under surface of the forearm. Laterally spaced fin members depend from lower portion of the strap and extend rearwardly and outwardly away from each other and move inwardly and outwardly in response to a forward return stroke and a rearward thrust stroke, respectively. Resilient means restrains outward movement of the fin members in proportion to the force applied to produce resistance to the water in proportion to the force applied.

ite l her States Patent [191 I SWIM FIN [76] Inventor: Alec Feather,1701 Sunrise Ln.,

Fullerton, Calif. 92633 22 Filed: Mar.,12, 1973 21 App1.No.:340,223

[52] [1.8. Cl. 9/307 [51] Int. Cl A631) 31/00 [58] Field of Search9/301, 303, 305, 307

[56] References Cited UNITED STATES PATENTS 1,760,476 5/1930 Chastenay9/303 1,821,974 9/1931 LeBlanc 1. 9/303 1,908,184 5/1933 Richmond 9/3031,983,609 12/1934 Hudson 9/305 X 3,107,371 10/1963 Thompson 9/307 X3,290,707 12/1966 Montgomery 9/307 FOREIGN PATENTS OR APPLICATIONS GreatBritain 9/307 [111 3,827,095 [451 Aug. 6, 1974 Primary Examiner-TrygveM. Blix Assistant Examiner-Gregory W. OConnor Attorney, Agent, orFirm-Jennings, Carter & Thompson [5 7] ABSTRACT A swim fin having asupport strap attachable to the forearm of a user with a lower portionof the strap extending transversely of the under surface of the forearm.Laterally spaced fin members depend from lower portion of the strap andextend rearwardly and outwardly away from each other and move inwardlyand outwardly in response to a forward return stroke and a rearwardthrust stroke, respectively. Resilient means restrains outward movementof the fin members in proportion to the force applied to produceresistance to the water in proportion to the force applied.

6 Claims, 4 Drawing Figures ]I SWIM FIN BACKGROUND OF THE INVENTION Thisinvention relates to a swim fin and more particularly to a swim finwhich is attachable to the forearm of a swimmer, surfer, skindiver orothers to aid in propelling the body of the user through water.

As is well known in the art to which my invention relates, lifeguardsand surfers need the use of their hands. Accordingly, hand paddles andother devices held within the hands are difficult to use. Also, handpaddles and the like heretofore employed have been unsatisfactory due tothe fact that it is difficult to adjust the operation of the device tothe strength of the individual user. That is, a strong swimmer wouldneed a maximum surface area to present to the water whereas a weaker ortired swimmer would need to present a much smaller surface area to thewater.

BRIEF SUMMARY OF THE INVENTION In accordance with my invention, Iprovide a swim fin having a support strap attachable to the forearm of auser, such as adjacent the wrist, with the lower portion of the strapextending transversely under the forearm. Rearwardly and outwardlyextending fin members depend from the under surface of the strap inspaced relation to each other. The fin members are movable inwardly andoutwardly in response to a forward return stroke and a rearward thruststroke, respectively. Outward movement of the fin members is restrainedby resilient means to present a surface area to the water in proportionto the force applied. Accordingly, the position of the fin members isadjusted automatically in response to variations in the force appliedwhereby the operation is adjusted to the strength of the individualuser.

DESCRIPTION OF THE DRAWING A swim fin embodying features of my inventionis illustrated in the accompanying drawing, forming a part of thisapplication, in which:

FIG. 1 is a side elevational view showing the swim fin in use;

FIG. 2 is a view taken generally along the line 2-2 of FIG. 1;

FIG. 3 is a bottom plane view showing the fiat position that the swimfin assumes when not in use; and,

FIG. 4 is a fragmental view taken generally along the line 4-4 of FIG.3.

DETAILED DESCRIPTION Referring now to the drawing for a betterunderstanding of my invention, I show a strap-like support member havingcooperating fastening elements 11 and 12 at opposite ends thereof. Thefastening elements 11 and 12 may be in the form of the usual strap andbuckle assembly or other fastening devices may be employed. Since suchfastening devices for strap-like elements are well known in the art, nofurther description thereof is deemed necessary. The strap-like member10 is adapted for attachment to the forearm 13 of a user and ispreferably attached adjacent the wrist, as shown in FIG. 1. However, thestrap-like member 10 may be attached to the hand or to the forearm at aposition inwardly of the wrist.

Formed integrally with the strap-like member 10 are a pair of laterallyspaced fin members 14 and 16 which depend from the lower portion of thestrap-like member 10 and extend from a location adjacent the forwardportion of said strap-like member rearwardly and outwardly away fromeach other, as shown in FIGS. 2 and 3 and define therebetween aninverted V-shaped recess having downwardly and outwardly extendingsides. The fin members 14 and 16 and the strap-like member 10 are formedof a resilient material. In actual practice, I have found that manyelastomeric materials, such as plastic, rubber and the like having ashore durometer hardness ranging from approximately 50 to 55 issatisfactory.

As shown in FIG. 2, the fin members 14 and 16 are adapted to move to aninner position with the front edges thereof adjacent and parallel toeach other, indicated by dotted lines 14a and 16a, in response to aforward return stroke and are adapted to move to an outer position,indicated by dotted lines 14b and 16b in response to a rearward thruststroke. According, as shown in FIG. 3, the fin members 14 and 16converge forwardly whereby a straight line passing through the front andrear edges of the fin member 14 would intersect a straight line passingthrough the front and rear edges of the fin member 16 at a pointforwardly of the fin members. As shown in FIG. 4, the fin members 14 and16 are positioned on the strap-like member 10 whereby they extend at anangle ranging from 10 to 25 away from a vertical plane passing throughthe strap-like member 10 and extending perpendicular thereto.Accordingly, upon making a forward, return stroke, very little pressureis required to move the fin members 14 and 16 inwardly to the dottedline positions 14a and 16a. In this position, the fin members extendgenerally parallel to each other and do not protrude beyond the sides ofthe forearm 13, thus offering a minimum of resistance on the returnstroke. On the rearward or thrust stroke, the fin members 14 and 16 areadapted to move outwardly a maximum distance of approximately from eachother in response to maximum force being applied whereby a maximumsurface area is presented to the water for resistance.

By forming the strap-like member 10 and the fin members 14 and 16 of aresilient material, the resilient material serves as means forrestraining movement of the fin members toward the outer dotted linepositions 14b and 16b in proportion to the force applied. That is, thefin members 14 and 16 move outwardly a decreasing angular distance foreach increase in force applied to produce resistance to the water inproportion to the force applied. As shown in FIGS. 3 and 4, inwardlyprojecting stiffening flanges 17 and 18 are provided at the forward andrear edges of the fin members 14 and 16 whereby it takes a greater forceto move the fin members from the solid line position shown in FIG. 2 tothe dotted line position shown at 14b and 16b.

From the foregoing description, the operation of my improved swim finwill be readily understood. The strap-like member 10 is attached to theforearm 13 of the user by the fastening elements 11 and 12 whereby thefin members 14 and 16 extend outwardly and rearwardly, as shown in FIG.2. As the arm is moved forward for the return stroke, the fin members 14and 16 move to the dotted line positions 14a and 16a whereby they are inalignmentwith the sides of the forearm 13. In this position, the finmembers 14 and 16 do not project beyond the sides of the forearm wherebya minimum of resistance isjoffered during the return stroke.

Upon making a rearward, thrust stroke,'the fin members 14 and 16 areforced outwardly toward the dotted line positions 14b and 16b. As theforce is increased on the thrust stroke, the resilient of the finmembers restrains movement toward the outer position in proportion tothe force applied. Accordingly, the tin members move outwardly adecreasing angular distance for each increase in force applied toproduce resistance to the water in proportion to the force applied. Astrong swimmer would thus supply sufficient force to move the finmembers 14 and 16 to the dotted line positions 14b and 16b whereby theyare approximately 180 from each other. On the other hand, a weaker ortired swimmer would not be able to exert the required force to move thefin members to the dotted line positions 14b and 16b. Accordingly, thefin members would assume a position between the solid line position andthe dotted line position 14b and 16b, depending upon the force exerted.That is, the fin members 14 and 16 would be automatically adjusted tothe proper position to accommodate the force being applied by theswimmer.

From the foregoing, it will be seen that l have devised an improved swimfin. By providing a swim fin which automatically adjusts itself to theforce applied by the swimmer, the swim fin is extremely efficient inoperation and at the same time does not impair the use of the hands ofthe swimmer. Also, by providing a swim fin which is attached to theforearm, the swim fin is comfortable to wear and the swimmer ispermitted to gain speed with less effort. Furthermore, by forming theswim fin of an elastomer, the entire swim fin may be formed as anintegral unit, thus facilitating manufacture.

While I have shown my invention in but one form, it will be obvious tothose skilled in the art that it is not so limited, but is susceptibleof various other changes and modifications without departing from thespirit thereof.

What I claim is:

1. A swim fin comprising,

a. a strap-like support member adapted for attachment to the forearm ofa user with a lower portion of said support member extendingtransversely of the under surface of said forearm,

b. a pair of laterally spaced fin members depending from said lowerportion and extending rearwardly and outwardly away from each other todefine an inverted V-shaped recess therebetween having downwardly andoutwardly extending sides which converge forwardly and are adapted tomove to an inner position in response to force being applied in aforward return stroke and to an outer position in response to forcebeing applied in a rearward thrust stroke, and

c. resilient means restraining movement of said fin members toward saidouter position in proportion to the force applied in a rearward thruststroke so that said fin members move outwardly a decreasing angulardistance in response to an increase in force applied to produceresistance to the water in proportion to the force applied.

2. A swim fin as defined in claim 1 in which said fin members areadapted to move outwardly a maximum distance of approximately l fromeach other in response to maximum force being applied during a thruststroke to present a maximum surface area to the water for resistance 3.A swim fin as defined in claim 1 in which said lower portion of saidsupport member extends transversely of the under surface of the wrist ofsaid forearm with each fin member extending at an angle ranging from 10to 25 away from a vertical plane passing through said support member andextending perpendicular thereto.

4. A swim fin as defined in claim 1 in which said support member andsaid fin members are formed integrally of a resilient material toprovide said resilient means restraining movement of said fin memberstoward said outer position.

5. A swim fin as defined in claim 4 in which said resilient material isan elastomer having a shore durometer hardness ranging fromapproximately 50 to 55.

6. A swim fin as defined in claim 1 in which inwardly projectingstiffening flanges are provided adjacent the ends of said fin members.

1. A swim fin comprising, a. a strap-like support member adapted forattachment to the forearm of a user with a lower portion of said supportmember extending transversely of the under surface of said forearm, b. apair of laterally spaced fin members depending from said lower portionand extending rearwardly and outwardly away from each other to define aninverted V-shaped recess therebetween having downwardly and outwardlyextending sides which converge forwardly and are adapted to move to aninner position in response to force being applied in a forward returnstroke and to an outer position in response to force being applied in arearward thrust stroke, and c. resilient means restraining movement ofsaid fin members toward said outer position in proportion to the forceapplied in a rearward thrust stroke so that said fin members moveoutwardly a decreasing angular distance in response to an increase inforce applied to produce resistance to the water in proportion to theforce applied.
 2. A swim fin as defined in claim 1 in which said finmembers are adapted to move outwardly a maximum distance ofapproximately 180* from each other in response to maximum force beingapplied during a thrust stroke to present a maximum surface area to thewater for resistance
 3. A swim fin as defined in claim 1 in which saidlower portion of said support member extends transversely of the undersurface of the wrist of said forearm with each fin member extending atan angle ranging from 10* to 25* away from a vertical plane passingthrough said support member and extending perpendicular thereto.
 4. Aswim fin as defined in claim 1 in which said support member and said finmembers are formed integrally of a resilient material to provide saidresilient means restraining movement of said fin members toward saidouter position.
 5. A swim fin as defined in claim 4 in which saidresilient material is an elastomer having a shore durometer hardnessranging from approximately 50 to
 55. 6. A swim fin as defined in claim 1in which inwardly projecting stiffening flanges are provided adjacentthe ends of said fin members. >